> Has anyone
> devised a way to hold the non-L-shaped deflectors in place?

As I wrote the other day: RTV.  I put a very small bead of black
RTV where the deflector met the window channel material on the
outside--with the window up.  Let it cure over night and it held
the deflector in place perfectly for several years.

When I wanted to remove the deflectors, I just sliced the bead
with a razor knife and removed and then cleaned the bead off
the deflector with my finger nail.

Or as someone else wrote, caulk.

Richard